Kinetics Of Decomposition Research Articles

Unravel the Spinodal Decomposition Kinetics in (FeCoCrNi)85(AlCu)15 Alloy through Small-Angle Neutron Scattering

Unravel the Spinodal Decomposition Kinetics in (FeCoCrNi)85(AlCu)15 Alloy through Small-Angle Neutron Scattering

Identifying the Role of Interfacial Long-Range Order in Regulating the Solid Electrolyte Interphase in Lithium Metal Batteries.

The self-assembled monolayer (SAM) technique, known for its customizable molecular segments and active end groups, is widely recognized as a powerful tool for regulating the interfacial properties of high-energy-density lithium metal batteries. However, it remains unclear how the degree of long-range order in SAMs affects the solid electrolyte interphase (SEI). In this study, we precisely controlled the hydrolysis of silanes to construct monolayers with varying degrees of long-range order and investigated their effects on the SEI nanostructure and lithium anode performance. The results indicate that the degree of long-range order in SAMs significantly influences the decomposition kinetics of the carbon-fluorine bond in lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), promoting the formation of a LiF-rich SEI and profoundly affecting the long-term stability of the highly sensitive anode during electrochemical processes. These findings provide new insights and directions for the molecular design of SAMs tailored for long-lasting lithium metal interfaces.

Characterisation of Varying Iron Ores and Their Thermal Decomposition Kinetics Under HIsarna Ironmaking Conditions

In the pre-reduction cyclone of the HIsarna process, both thermal decomposition and gas reduction of the injected iron ores occur simultaneously at gas temperatures of 1723–1773 K. In this study, the kinetics of the thermal decomposition of three iron ores (namely OreA, OreB and OreC) for HIsarna ironmaking were analysed as an isolated process with a symmetrical thermogravimetric analyser (TGA) under an inert atmosphere. Using various methods, the chemical and mineralogical composition, particle size distribution, morphology and phase distribution of the ores were analysed. The ores differ in their mineralogy and morphology, where OreA only contains hematite as iron-bearing phase and OreB and OreC include goethite and hematite. To obtain the kinetic parameters in non-isothermal conditions, the Coats–Redfern Integral Method was applied for heating rates of 1, 2 and 5 K/min and a maximum temperature of 1773 K. The TGA results indicate that goethite and hematite decomposition occur as a two-stage process in an inert atmosphere of Ar. The proposed reaction mechanism for the first stage of goethite decomposition is chemical reaction with an activation energy ranging from 46.55 to 60.38 kJ/mol for OreB and from 69.90 to 134.47 kJ/mol for OreC. The proposed reaction mechanism for the second stage of goethite decomposition is diffusion, showing an activation energy ranging between 24.43 and 44.76 kJ/mol for OreB and between 3.32 and 23.29 kJ/mol for OreC. In terms of hematite decomposition, only the first stage was analysed. The proposed reaction mechanism is chemical reaction control. OreA shows an activation energy of 545.47 to 670.50 kJ/mol, OreB one of 587.68 to 831.54 kJ/mol and OreC one of 424.31 to 592.32 kJ/mol.

Theory‐Guided Design of Unconventional Phase Metal Heteronanostructures for Higher‐Rate Stable Li‐CO2 and Li‐Air Batteries

AbstractLithium‐carbon dioxide (Li‐CO2) and Li‐air batteries hold great potential in achieving carbon neutral given their ultrahigh theoretical energy density and eco‐friendly features. However, these Li‐gas batteries still suffer from low discharging‐charging rate and poor cycling life due to sluggish decomposition kinetics of discharge products especially Li2CO3. Here we report the theory‐guided design and preparation of unconventional phase metal heteronanostructures as cathode catalysts for high‐performance Li‐CO2/air batteries. The assembled Li‐CO2 cells with unconventional phase 4H/face‐centered cubic (fcc) ruthenium‐nickel heteronanostructures deliver a narrow discharge‐charge gap of 0.65 V, excellent rate capability and long‐term cycling stability over 200 cycles at 250 mA g−1. The constructed Li‐air batteries can steadily run for above 150 cycles in ambient air. Electrochemical mechanism studies reveal that 4H/fcc Ru−Ni with high‐electroactivity facets can boost redox reaction kinetics and tune discharge reactions towards Li2C2O4 path, alleviating electrolyte/catalyst failures induced by the aggressive singlet oxygen from solo decomposition of Li2CO3.

Identify the key factors driving the lignocellulose degradation of litter along a forest succession chronosequence from the perspective of functional genes

The purpose of this paper was to discover the key factors driving the lignocellulose degradation in litter along a forest succession chronosequence from the perspective of functional genes. We investigated four natural successive stages of forests (white birch forest, broad-leaved mixed forest, coniferous-broad-leaved mixed forest, and mixed broadleaved-Korean pine forest). We determined the lignocellulose degradation of litter and the absolute abundance of related functional genes by using high-throughput-qPCR. There was strong degradation of cellulose content, hemicellulose, and lignin contents in the litter decomposition layer in the early and late stages of forest succession, respectively. Furthermore, forest succession changed microbial communities' succession and fungal Shannon diversity, and then enhanced the absolute abundance of lignocellulose-degrading genes and nitrogen-cycling genes. By network analysis, bacterial and fungal module 1 were key modules for producing lignocellulose-degrading genes and nitrogen cycling genes, while fungal module 2 was a key module for lignin-degrading genes. Fungi were strongly correlated with functional genes based on Procrustes analysis. Additionally, cellulose-degrading genes were the key factor driving the cellulose degradation in the early period of forest succession, while fungal diversity and composition were key drivers in promoting the degradation of lignin in the late period of forest succession. Our study provided insight into the mechanisms underlying the soil microbe-driven functional changes in nutrient cycling and an understanding of the decomposition kinetics of litter at a more microscopic level in the process of forest succession.

Tuning Reaction Kinetics of Fluorinated Molecules to Construct Robust Solid Electrolyte Interphases on SiOx Anode.

Introducing fluorinated electrolyte additives to construct LiF-rich solid-electrolyte interphase (SEI) on Si-based anodes is proven an effective strategy for coping with its massive volume changes during cycling. However, most current research on fluorine-containing additives focuses on their thermodynamics of decomposition, lacking studies on the correlation between the molecular structure of additives and their decomposition kinetics. Herein, two fluorinated ester additives, diethyl fluoromalonate (F1DEM) and diethyl 2,2-difluoromalonate (F2DEM) were designed and synthesized. Through combining a wealth of characterizations and simulations, it is revealed that despite the similar reduction thermodynamics, the favorable reduction kinetics of single-fluorinated F1DEM facilitate a LiF-rich layer during the early stage of SEI formation, contributing to the formation of a more robust SEI on SiOx anode compared to the difluorinated F2DEM. Consequently, the proposed additive achieves excellent cycling stability (84 % capacity retention after 1000 cycles) for 5 Ah 21700 cylindrical batteries under practical testing conditions. By unveiling the role of reaction kinetics, a long-overlooked aspect for the study of electrolyte additives, this work sheds light on how to construct a stable SEI on Si-based anodes.

Tuning Reaction Kinetics of Fluorinated Molecules to Construct Robust Solid Electrolyte Interphases on SiOx Anode

AbstractIntroducing fluorinated electrolyte additives to construct LiF‐rich solid‐electrolyte interphase (SEI) on Si‐based anodes is proven an effective strategy for coping with its massive volume changes during cycling. However, most current research on fluorine‐containing additives focuses on their thermodynamics of decomposition, lacking studies on the correlation between the molecular structure of additives and their decomposition kinetics. Herein, two fluorinated ester additives, diethyl fluoromalonate (F1DEM) and diethyl 2,2‐difluoromalonate (F2DEM) were designed and synthesized. Through combining a wealth of characterizations and simulations, it is revealed that despite the similar reduction thermodynamics, the favorable reduction kinetics of single‐fluorinated F1DEM facilitate a LiF‐rich layer during the early stage of SEI formation, contributing to the formation of a more robust SEI on SiOx anode compared to the difluorinated F2DEM. Consequently, the proposed additive achieves excellent cycling stability (84 % capacity retention after 1000 cycles) for 5 Ah 21700 cylindrical batteries under practical testing conditions. By unveiling the role of reaction kinetics, a long‐overlooked aspect for the study of electrolyte additives, this work sheds light on how to construct a stable SEI on Si‐based anodes.

Syntheses, Structures, and Thermal Decomposition Kinetics of Two Silver/Copper‐Based Coordination Compounds with 1,2,4‐Triazole‐Containing Ligand

AbstractIn this work, two silver/copper‐based coordination compounds {[Ag(tty)]⋅NO3}n (1) and {[Cu2Cl2(tty)2(H2O)2]⋅Cl⋅NO3 ⋅ (H2O)2}n (2) (tty=1,2,4,5‐tetra(1H‐1,2,4‐triazol‐1‐yl))benzen), were synthesized using the different metal salts under the hydrothermal condition. Structural analyses show that compound 1 features tilted L‐shaped 1D Ag chains structure and compound 2 presents a 2D layer with free Cl−, NO3− and water molecules. The experimental results reveal that 1 displays considerably high thermal stability with the thermal decomposition temperature above 337 °C compared to compound 2, which further exemplifies that the framework structures may have a crucial effect on the resultant thermal stability. Additionally, the non‐isothermal kinetics parameters were evaluated at different heating rates by Kissinger's and Ozawa‐Doyle's methods. Importantly, the kinetic triplets (the apparent activation energy (Ea), the preexponential factor (logA) and the mechanism function (ƒ(α)) and the related thermodynamic parameters (the Gibbs energy of activation, ▵G≠, the enthalpy of activation, ▵H≠, and the entropy of activation, ▵S≠) of the thermal decomposition processes are discussed and calculated in detail.

Screening of F-containing electrolyte additives and clarifying their decomposition routes for stable Li metal anodes.

Constructing a LiF-rich solid electrolyte interphase (SEI) is a feasible strategy for inhibiting lithium (Li) dendrites of Li metal anodes (LMAs). However, selecting appropriate F-containing additives with efficient LiF contribution is still under active research. Herein, a series of fluorinated additives with diverse F/C molar ratios are investigated, and we demonstrate that the hexafluoroglutaric anhydride (F6-0) holds the best capability to derive the LiF-rich SEI in regular carbonate electrolytes (RCEs). To ameliorate the decomposition kinetics of the F6-0, LiNO3 (LNO) as an adjuvant is further introduced in the system. As a result, the reduction efficiency of F6-0 is increased to 91% under the F6-0/LNO synergistic effect, enabling the LMA with a uniform LiF-rich SEI in the RCE with merely 4 vol. % F6-0/LNO (F6L) addition. The LiNi0.8Co0.1Mn0.1O2||Li-20μm full-cell with the F6L also showcases better cycling and rate performances than the cases with other F-containing additives.

The Impact of Activated Carbon–MexOy (Me = Bi, Mo, Zn) Additives on the Thermal Decomposition Kinetics of the Ammonium Nitrate–Magnesium–Nitrocellulose Composite

This research investigates the impact of additives such as activated carbon (AC) combined with metal oxides (Bi2O3, MoO3, and ZnO) on the thermal decomposition kinetics of ammonium nitrate (AN), magnesium (Mg), and nitrocellulose (NC) as a basic AN–Mg–NC composite. To study the thermal properties of the AN–Mg–NC composite with and without the AC–MexOy (Me = Bi, Mo, Zn) additive, a differential scanning calorimetry (DSC) analysis was conducted. The DSC results show that the AC–MexOy (Me = Bi, Mo, Zn) additive catalytically affects the basic AN–Mg–NC composite, lowering the peak decomposition temperature (Tmax) from 534.58 K (AN–Mg–NC) to 490.15 K (with the addition of AC), 490.76 K (with AC–Bi2O3), 492.17 K (with AC–MoO3), and 492.38 K (with AC–ZnO) at a heating rate of β equal to 5 K/min. Based on the DSC data, the activation energies (Ea) for the AN–Mg–NC, AN–Mg–NC–AC, and AN–Mg–NC–AC–MexOy (Me = Bi, Mo, Zn) composites were determined using the Kissinger method. The results suggest that incorporating AC and AC–MexOy (Me = Bi, Mo, Zn) additives reduce the decomposition temperatures and activation energies of the basic AN–Mg–NC composite. Specifically, Ea decreased from 99.02 kJ/mol (for AN–Mg–NC) to 93.63 kJ/mol (with addition of AC), 91.45 kJ/mol (with AC–Bi2O3), 91.65 kJ/mol (with AC–MoO3), and 91.76 kJ/mol (with AC–ZnO). These findings underscore the potential of using AC–MexOy (Me = Bi, Mo, Zn) as a catalytic additive to enhance the performance of AN–Mg–NC-based energetic materials, increasing their efficiency and reliability for use in solid propellants.

Considerations for the safe handling and processing of unstable materials

AbstractWe evaluate the instability hazards of initiators, monomers, and other unstable materials during storage and handling in individual containers, pallets of containers, and storage and process vessels. We propose a simplistic model to analyze the temperature–time profile of an unstable chemical, given heat transfer from/to the environment, heat generation due to decomposition and other reaction kinetics, and heat generated from auxiliary equipment (e.g., agitators/mixers, pumps, vessel jackets). Lumped capacitance‐based heat transfer and decomposition kinetics are integrated to predict self‐accelerating decomposition temperature (SADT), self‐accelerating polymerization temperature (SAPT), and the temperature profile given exposure conditions (e.g., ambient temperature and additional sources of heat). Case studies related to the storage and processing of unstable liquid monomers (i.e., methyl methacrylate, MMA), and organic peroxides, (i.e., tert‐butyl peroxybenzoate, TBPB), are presented. We also provide recommendations on determining safe storage and processing temperatures and steps to prevent emergency situations and include an overview of thermal analysis and data treatment procedures which might affect chemical process safety recommendations.

Solvent Effect on Decomposition Kinetics of Ammonium Carbamate for a Chemical Heat Pump

Solvent Effect on Decomposition Kinetics of Ammonium Carbamate for a Chemical Heat Pump

Kerogen geochemistry and thermal decomposition kinetics of Early Permian shales from the Talchir Basin of Odisha, Eastern India

Kerogen geochemistry and thermal decomposition kinetics of Early Permian shales from the Talchir Basin of Odisha, Eastern India

Engineering Optimization of Producing High-Purity Dichlorosilane in a Fixed-Bed Reactor by Trichlorosilane Decomposition.

High-purity dichlorosilane (DCS) is an important raw material for thin film deposition in the semiconductor industry, such as epitaxial silicon, which is mainly produced by trichlorosilane (TCS) catalytic decomposition in a fixed-bed reactor. The productivity of DCS is strongly dependent on the controlling of the TCS decomposition reaction process, associated with the cost in practical application. In this study, we have performed computational fluid dynamics (CFD) simulation on the TCS decomposition reaction kinetics in a cylindrical fixed-bed reactor, in which the effects of catalyst bed height, feed temperature, and feed flow rate are stressed to predict the conversion rate of TCS and the generation rate of DCS. This indicates that the increase of bed height helps the reaction to proceed adequately, but too large a bed height does not improve the DCS generation rate. Meanwhile, the feed temperature and reactor temperature have important effects on the DCS generation rate. However, it is found that changing the feed flow rate and L/D ratio cannot effectively improve the DCS generation rate while the bed volume remains constant. Furthermore, we have designed a fixed-bed reactor to verify the simulation results, which are in good agreement with each other. These results are of significance for the practical industrial production of high-purity DCS in a fixed-bed reactor.

Investigation of halloysite thermal decomposition through differential thermal analysis (DTA): Mechanism and kinetics assessment

The study focused on analysing the kinetics of halloysite decomposition using the differential thermal analysis (DTA) technique. Tests were carried out across a temperature span from ambient temperature to 1673 K, employing heating rates spanning from 5 to 20 °C.min−1. X-ray diffraction and Fourier transform infrared spectroscopy (FT-IR) were utilized to identify the phases formed at different temperatures. Activation energies for halloysite decomposition were determined through isothermal and non-isothermal treatments, yielding values of approximately 151.68 kJ mol−1 and 173.14 kJ mol−1, respectively. The Ligero method's Avrami constant parameter (n) and the Matusita method's numerical factor parameter (m), linked to crystal growth dimensions, were both around 1.5. These findings indicate that the degradation of halloysite is primarily governed by bulk nucleation, succeeded by the 3-dimensional growth of meta-halloysite characterized by polyhedron-like structure, regulated by diffusion from a consistent number of nuclei. The frequency factor for halloysite dehydroxylation was established at 8.48 × 10⁸ s⁻1.

Systematical analysis and application of distributed activation energy model (DAEM) with Weibull distribution for pyrolysis kinetics of lignocellulosic biomass

The distributed activation energy model (DAEM) is a comprehensive and accurate kinetic model for describing the thermal decomposition kinetics of complex materials. The Gaussian distribution is commonly used for representing the activation energy distribution, however, it is symmetric and cannot reflect the reactivity asymmetry involved in complex chemical kinetics. The Weibull distribution offers an alternative to represent the distribution of activation energies. This study performed a systematical investigation of the DAEM with Weibull distribution, focusing particularly on its asymmetric characteristics. Additionally, the DAEM with Weibull distribution was applied to analyze the pyrolysis kinetics of rice straw and cotton stalk. The theoretical analysis results showed that the DAEM with Weibull distribution could provide abundant flexibility to elucidate the asymmetric reactivity of complex chemical kinetics. The pyrolysis processes of rice straw and cotton stalk could be deconvoluted into several sub-processes, which could be accurately described by the DAEMs with Weibull distribution. The obtained Weibull distributions of activation energies for those deconvoluted sub-processes validated their asymmetric reactivities. It is expected that the results could help in exploring the kinetic mechanisms of lignocellulosic biomass pyrolysis and facilitate the application of the DAEM with Weibull distribution in analyzing complex chemical kinetics.

Ammonium perchlorate catalyzed with novel n-Al modified on ZIF-67 with silane coupling agent: Superior catalytic activity, advanced decomposition kinetics and mechanisms

Ammonium perchlorate (AP) is commonly utilized as an oxidizer in composite solid propellants (CSPs), and the thermal decomposition of AP has a significant impact on the combustion behaviour of CSPs. Aluminum nanoparticles (n-Al) as a prospective metal fuel have received a lot of interest, however properly extracting energy from n-Al remains a great challenge. Native oxide layer limits the energetic performance of n-Al by impeding sufficient combustion and slowing down mass/heat transport. Development of the high energy storage based on metastable intermolecular composite (MIC) is always a desirable way. This group of hybrid materials uses zeolitic imidazole framework (ZIF) as the precursors of the metal oxides as the oxidizers in conventional nanothermite. Coating n-Al on the surface of ZIF-67 with a silane coupling agent to erase or disturb the oxide layer on the n-Al surface improves n-Al combustion. n-Al@ZIF-67 was synthesized and integrated into AP matrix. The catalytic activity of n-Al@ZIF-67 on AP decomposition was assessed via DSC and TGA/DTG. Whereas n-Al@ZIF-67/AP nanocomposite demonstrated decomposition enthalpy of 2350 J/g; pure AP demonstrated 836 J/g, ZIF-67/AP demonstrated 1680 J/g, and n-Al/AP demonstrated 1170 J/g. While Al@ZIF-67/AP nanocomposite demonstrated one decomposition temperature at 327 oC; pure AP decompose at two decomposition stages at 298 oC, and 453 oC. n-Al@ZIF-67/AP showed a violent reaction with high intensity of flame, and micro-explosion occurred due to rapidly disrupted oxide layer that covered Al core. Decomposition kinetics was investigated. n-Al@ZIF-67/AP demonstrated apparent activation energy of 125.3 ± 1.23 kJ/mol compared with 173.16 ± 1.95 kJ/mol for pure AP. Co3O4 NPs as the combustion product from ZIF-67 can expose active surface sites; the ability of adsorption of released NH3 gas, which inhibition AP from decomposition, offering efficient combustion. This work provides a new strategy for advanced CSPs by introducing ZIF-67 to construct bifunctional properties for AP decomposition, and n-Al combustion.

Operando visualization of porous metal additive manufacturing with foaming agents through high-speed x-ray imaging

Porous metals find extensive applications in soundproofing, filtration, catalysis, and energy-absorbing structures, thanks to their unique internal pore structure and high specific strength. In recent years, there has been an increasing interest in fabricating porous metals using additive manufacturing (AM), leveraging its unique advantages, including improved design freedom, spatial material control, and cost-effective small-batch production. In this study, we conducted pioneering operando visualization of AM porous metal using a laser powder bed fusion (L-PBF) setup combined with a high-speed synchrotron x-ray imaging system. Single track printing experiments using Ti6Al4V (Ti64) combined with titanium hydride (TiH2) and sodium carbonate (Na2CO3) as foaming agents, with varying mixing ratios were performed under different processing conditions. The results elucidate the dynamic development of porosity formation. The average pore size is significantly influenced by the particle size of foaming agents when pore coalescence is absent. For all foaming agent content tested in the current study, the number of pores is found to be more sensitive to changes in laser power than in laser scanning speed. Increasing linear energy density (increasing laser power or reducing laser scanning speed) promotes the foaming agent activation thereby porosity formation. However, high linear energy density skews pore distribution towards the surface despite forming deeper melt pools. In addition, the impact of additional factors including foaming agent’s laser absorptivity and decomposition kinetics with respect to AM time scales should be carefully considered to avoid ineffective activation of foaming agents during the AM of porous metals.

Investigation of the impurity effect on the kinetics of thermal decomposition of natural gypsum at high temperatures

Natural gypsum is the most common sulfate on our planet, which is widely used in construction due to its excellent astringent properties, environmental friendliness, thermal and fire resistance, accessibility in nature and low price. Currently, the influence of modifiers, impurities and additives that can improve the strength, acoustic and thermal insulation characteristics of gypsum, which is so important in modern architecture, construction and reducing power consumption, is being increasingly studied. However, additives and impurities, controlled and uncontrolled, as in natural gypsum, can unpredictably affect the thermal stability and fire resistance of gypsum. The purpose of our work is to study the thermal characteristics of gypsum from various deposits in a wide temperature range. Our work shows that the temperature and rate of dissociation of gypsum directly depends on impurities that can change the process of its decomposition. As a result of the decomposition of natural gypsum with impurities, new phases are formed.It has been experimentally shown that the process of thermal destruction of gypsum with impurities has a complex multistage character, which is described by successive reactions of the nth order of the Avrami-Erofeev equation. It can be assumed that the reaction mechanism consists in the rapid formation of numerous nucleation centers on the surface of solid anhydrite. Kinetic parameters of thermal decomposition of gypsum of complex composition and phase formation at high temperatures are calculated. This experimental study shows the dependence of thermal stability on the amount and grade of impurities in gypsum. The results obtained contribute to the improvement of the basic concepts of the mechanism of decomposition of gypsum, as well as the explanation of some high-temperature phase formation processes in nature.

Thermodynamics and kinetics of evaporation and thermal decomposition of 1-ethyl- and 1-butyl-3-methylimidazolium methanesulfonate ionic liquids: Experimental and computational study

Knudsen cell mass spectrometry was used to study the evaporation of two ionic liquids, 1-ethyl-3-methylimidazolium methanesulfonate ([EtMIm][MS], MS = CH3SO3) and 1-butyl-3-methylimidazolium methanesulfonate ([BuMIm][MS]), accompanied by thermal decomposition (thermolysis). The independent occurrence of evaporation and thermolysis reactions made it possible to determine their thermodynamic and kinetic characteristics under identical experimental conditions. The saturated vapor pressures were measured and the standard enthalpies of vaporization of [EtMIm][MS](l) and [BuMIm][MS](l) were obtained. The standard thermodynamic functions of formation in the liquid and gaseous states at 298.15 K were estimated from the available experimental data and the results of quantum chemical calculations. The gaseous decomposition products of ionic liquids were identified and the pressures of the thermolysis products of [EtMIm][MS](l) were determined. According to the experimental data and quantum chemical calculations, the thermolysis of [EtMIm][MS](l) occurs through heterogeneous reactions far from the equilibrium state. The kinetics of the reactions is described in two ways. When the degree of sample conversion is used as a variable, the constant reaction rates at the initial stage of thermolysis correspond to a pseudo-zero order reaction with a monotonic increase in the degree of conversion. In the proposed alternative approach, the reaction rates are estimated from the fluxes of thermolysis products and are expressed in terms of ionic liquid concentration.